Greig Cowan answered on 25 Jun 2014:
Hi bethsinar. Some scientists do believe that there are other universes, in fact they believe that there are an infinite number of them! However, there is currently no evidence to support this idea, so it is really just a theory at the moment. These universes will all be slightly different, covering all possible combinations of matter, energy and the laws of physics. I don’t think there is any connection between there being other planets and their being other Universes.
Laurence Perreault Levasseur answered on 25 Jun 2014:
Yes, there could be. However they are not ‘other’ or ‘parallel’ universes in the sense of in the same physical place as us, and in a different level of reality. Rather, they are just so far away from us that they are beyond our observable Universe.
Observable Universe is a fancy word to say the furthest stuff we can see in the Universe because light has had time to travel from that stuff to us since the Big Bang. Everything beyond that is so far that light hasn’t had time to reach us, so we can’t see it.
So. How do other universes come about then? It’s because just after the Big Bang there was a period of inflation, when space was expanding exponentially fast. During that time, tiny pieces of space were stretched well beyond the size of the observable Universe today. Now if we imagine that inflation ended in some parts of the Universe, but not everywhere at the same time. Then, say, here, in a little bubble, inflation has ended, and our normal Universe as we see it starts evolving. But everywhere outside that bubble, the Universe is still expanding like crazy and inflation is still going on!
Then in a little bubble somewhere else inflation ends at a different time, and another universe start evolving, with similar properties as our own, but maybe slightly different, because, after all, it’s not the same place, nor the same Universe!!
Even with those two bubble universes, there is still a lot of space in inflation, and the amount of space in inflation is MUCH bigger (and constantly becomes MUCH MUCH bigger) than the space where inflation has stopped. So I can basically create an infinite amount of ‘little’ (I mean, they are still bigger than our observable universe today!!!) bubble Universes, and still have even more space in inflation, outside of those bubbles.
They will all be different, be at different places, and have different stuff in it. But you can really thin kof those as different Universes. This theory where some part of space is always in inflation is called ‘eternal inflation’ and the ensemble of all the bubble universes is called the ‘multiverse’.
This theory has some problems to it, though. Since to test it we’d have to go outside of our observable universe, which it’s impossible, it doesn’t yet make any testable prediction (yet). This means that many scientists think it’s not a scientific theory, because it cannot be falsified by experiment.
Aimee Hopper answered on 25 Jun 2014:
as far as we know, we cant directly “prove” the existance of other universes, because we can only see as far as light has travelled in the time from the big bang to today. Our Observable Universe is about 13 billion years old, but this may not be the edge of our own universe, let alone the start of another one.
it’s an interesting way to think about this though. I suppose a few hundred years ago people couldnt imagine other planets because we didn’t have the technology to see them. So maybe we are just waiting on some awesome new piece of technology to shed more light on this (pun not intended 😛 )
Dave Jones answered on 25 Jun 2014:
I think we need to make a distinction between Universe and planet. Universe is the word that we use to describe everything that we see, the space in which we are. This contains billions of galaxies, each galaxy containing billions of stars and most of those stars having at least a planet or two. So, the fact that there are lots of other planets doesn’t mean that there are other Universes, because all those other planets that we’ve found are actually in the same Universe as us!
But, that doesn’t mean that there aren’t other Universes. Some of the theories that people use to explain the properties of our Universe and how it behaves, need there to be other Universes, Universes that we can’t see. Because we can’t see them (by their very nature), these theories are almost impossible to prove!